New Windows

greenface2

window night latches do not pass doc f . If there is no sign of permanent ventilation in the room then trickle vents MUST be fitted into the windows / Used to be like for like of no worse . all changed last month . There are few ways to bypass this new and silly ruling into existing houses  (not new) which I will keep to myself  

BUFF

Scotland is different ...
https://www.gov.scot/publications/building-standards-technical-handbook-2020-domestic/3-environment/3-14-ventilation/

3.14.6 Trickle ventilators

A trickle ventilator, sometimes called 'background ventilation', is a small ventilation opening, normally provided with a controllable shutter. Although routinely provided in the head of a window frame this is often not the best location 

It also has:

Alternatives to proprietary trickle ventilators

The next changes afaik are still at the consultation stage.